I’m sure this is the to-do list but I thought I would add it just so there was a record.
While editing and adjusting traces on the board it would be useful to be able to select either whole or part and push it to a different layer. Even if it meant manually adding vias.
Is see this working as follows: Select a portion or portions of the trace to move, right click and then either select “Select Whole Trace” or “Move to Layer - layer_name”.